The present invention relates generally to the field of temperature-controlled display devices (e.g., refrigerated display devices or cases, etc.) having a temperature-controlled space for storing and displaying products such as refrigerated foods or other perishable objects. More specifically, the present invention relates to refrigeration system for a temperature-controlled display device. More specifically still, the present invention relates to a refrigeration system for a temperature-controlled display device that uses a brushless DC motor to circulate a refrigerant within a refrigeration circuit.
Temperature-controlled display devices (e.g., refrigerators, freezers, refrigerated merchandisers, refrigerated display cases, etc.) may be used in commercial, institutional, and residential applications for storing or displaying refrigerated or frozen objects. Refrigerated display cases are a type of temperature-controlled storage device that are often used to display fresh food products (e.g., beef, pork, poultry, fish, etc.) in a supermarket or other commercial setting. Refrigerated display cases typically include cooling elements (e.g., cooling coils, heat exchangers, evaporators, etc.) that receive a coolant (e.g., a liquid such as a glycol-water mixture, a refrigerant, etc.) from a refrigeration system to provide cooling to the temperature-controlled space. Fans are typically used to move air over the cooling elements to facilitate heat transfer thereto. Some refrigerated display cases have doors that can be opened (e.g., by a customer) to access products within the temperature-controlled space. Other refrigerated display cases have an open front and use fans to create an air barrier (e.g., an air curtain) to prevent outside air from entering the temperature-controlled space.
Some commercial refrigeration systems (e.g., in a supermarket) use centralized parallel compressor systems with long liquid and suction branches piped to and from the evaporators in the refrigerated display cases. However, remotely locating elements of the refrigeration system (e.g., compressors, condensers) can result in expensive field piping, large refrigerant charge and leakage, and parasitic heating of the liquid and suction piping. Other commercial refrigeration systems use self-contained refrigerated display cases that include all of the components of the refrigeration system (e.g., contained within a housing of the display case, positioned on top of the display case, etc.).
The compressors used in conventional refrigeration systems often suffer from a variety of disadvantages such as a lack of variable capacity, energy inefficiency, excess noise, etc. It would be desirable to provide a refrigerated display case with an improved compressor that overcomes these and other disadvantages.